Streambank Restoration in the Plum Creek

A local landowner had been growing increasingly concerned with a section of the unnamed Plum Creek tributary that is located on his property. Continual water action was causing the streambank walls of this section of the stream to develop unstable characteristics in many locations. The stream in this area has developed a meandering course which causes high erosion in the sections with sharp angled bends. The outside of these bends, where the water velocities are highest, is where the worst erosion was occurring. The erosion was undercutting the banks which was leading to a loss of stability and eventually causing the ground above to slough off, moving the bend closer and closer to the landowner’s home and a busy road. During one large rain event in December of 2015 more than one horizontal foot of material, equivalent to about one full dump truck, was lost in the outside bend.

In order to prevent this from happening, an integrated bank protection design plan was developed. The plan consisted of streambank shaping, rocking, and seeding. Slope shaping was utilized to pull back and stabilize the banks at a 2:1 or flatter slope. Along the outside bend, where the highest velocities occur, 8 inches of D50 4” diameter rock riprap was added to the graded slopes. A geotextile material was installed below the rock riprap in order to prevent water from seeping in to the pores between the rocks and pulling out the soil. A section of the stream after the outside bend was also stabilized by grading to a 2:1 or flatter slope. A shade and water tolerant, primarily grass seed mix was added in all disturbed areas along with a cover crop of oats to establish some immediate vegetation to help prevent erosion. Erosion matting was also installed above the rock riprap and along the vegetated portion of the newly shaped streambank in order to prevent erosion before the vegetation is established. The installation of this integrated bank system should help with the erosion problem that the landowner was facing.

This streambank restoration project was completed as part of the Plum and Konkapot Watershed Recovery project funded through Great Lakes Restoration Initiative Grants secured by the Fox-Wolf Watershed Alliance and Wisconsin Targeted Runoff Management Grant secured by Outagamie County.  The Plum and Konkapot Creek subwatersheds was prioritized in the TMDL agricultural implementation plan.

Originally posted on 11.21.16 by Outagamie County.